Here is the full list of all 31 Pummel Party achievements.
Win your first game
Get your first goal
Died in 'Acidic Atoll' throwing a barrel
Win your first minigame
Start your first game
Take no damage in 'Searing Spotlights' minigame
Accidentally blew yourself up in the 'Strategic Shockwave' minigame
Hit three players with the remote control eggplant
Skewer three players with the rocket skewer item
Place first in every minigame
Place last in every minigame
Get a double kill in 'Barn Brawl'
Survive for 50 seconds in 'Bullet Barrage'
Control over 50% of the area in 'Elemental Escalation'
As the lightning holder kill every other player in 'Thunderous Trench'
Knockout 10 players in one game of 'Explosive Exchange'
Complete 'Rusty Racers' without falling off the track
Survive for at least 50 seconds in 'Sorcerers Sprint'
Got hit by the train in 'Temporal Trails'
Knock off 5 players in one game of 'Snowy Spin'
Get a 5 player kill sreak in 'Speedy Sabers'
Get launched off screen in 'Tunneling Tanks'
Find the treasure in 'Sandy Search'
Win 'Magma & Mages' without taking damage
Collect 40 keys in 'Winter Maze'
Survive in 'Breaking Blocks' for 60 seconds
Steal the last gift in a players pile in 'Grifting Gifts'
Complete 'Slippery Sprint' without falling in the water
Score over 5 in 'Bouncing Balls'
Complete 'Gift Grab' without collecting coal